Sheave



Feb. 8, 1944; D. FIRTH ETAL 2,341,272

sHEAvE Filed Aug. 6, 1942 2 Sheets-Sheet 1 kx MMMWQQQ@ M j/ j@ l l Feb 8 19 D. FIRTH ET SHEAVE Flled Aug. 6, 1942 2 Sheet Sh y Y seet 2 Patented Feb. 8, 1944 TENT OF-'FICE SHEAVE 'David Firth, 'South Bend, and"D onald` PfLower,

Mishawaka, Ind., assignors to `Dodge LManu- Vfacturing Corporation, Mishawaka, Ind., a :cor-

`'poration of Indiana Application-August 6, 1942,Serial No.- 453,830

-9 Claims.

This invention, pertainingto sheaves,.has been evolved inganeffort to furtherthe national campaign of conservation of metals. In the present emergency it becomes important to conserve cast iron in addition to-other metals. This invention contemplates effecting .-alsubstantia] saving of metal by the utilization vof :Wood orother suitable non-metallic lmaterial -for the construction of sheaves formultiple Vbelt drives `and other machinery drives A,of the -beltv and q sheave type.

A feature of the invention is1the provision of a non-metallicksheavewithpracticable means ior securing it tothe sheave shaft, this being of importance for a non-Inetallic-sheave ofthe block type or of the type having .a non-contractible hub. Another feature is-thefprovision ofA a daminated Woodsheave `body of ,advantage with respect to dispositionof `the grain iof the wcodand also ofspe cial advantage for along sheave having a plurality of belt `grooves in -an overhanging portion which extendsibeyond thel end-of the moltor shafton whichthe sheave is mounted. With respect to the lastmentionecl feature, the invention is also-applicableto a Wood sheave of the Web type lhaving anlextending rim portion provided With-such grooves.

Cast iron -sheaves lof vthe block type are used extensively in multipleV-fbeltdrives. The invention has particularly in contemplation the production of -Wood sheaves -in the same forms and sizes as lsuch cast iron sheaves. The invention aims to .provide strong and .ecient structures, of practicable character, vsusceptible lof economical manufacture and serviceablefforduties for which such cast iron sheaves Aare eommonlyemployed.

`sheave similar to that of Fig. 1 and embodying additional features.

Fig. 5 vis va central longitudinal section of a sheave differing from the others in its-formand bodyconstruction butembodying in Ycommon with theothers the novel means hereindisolosed for securing `the-sheave to its shaft.

In Figs. 1., 2, and 3. a non-metallicsheave-body is `rept.stellte@ by faiblock I5 o f ninular `^cross .sectiony ,composedfoadhesively united `Wood plies yor laminations,preferably of hardwood such for example as-hard,maple, these plies or laminations being arrangedparallel with the sheave axisfandv extending fromend tofend ofthe sheave `.Fitted therein isaWOOdbuShing/IS through which thesheavabody isfsupported onfa motor-.shaft 2D. It .will ,be observed `that .a plurality of the belt grooves Llareinan .overhanging portion of the sheave body-Which extendsv beyond-the .endofthe motorshaft. .Such overhanging portion ofthe sheave body is 'subjectedto bending..and.shearing forces imposedby the .tensionof ,the belts which engage the-.groovesin such overhanging portion. In this Aconnection the described structurecf the ,sheave body .is V.,of I particular advantage. Not only does it give F.the great strengthpf a laminated wood structure, `but ,a1so,1by.virtue ofthe .arrangement ,of the Wood ,plies `or laminatiOnS,

there is no ,transversejoint which mustsustain ,the ,load imposed .by the tension o'f vthe ,belts .ion the ,overhangingeportionof the .sheave body. All of the belts concurrently .engage the same fWood components, which ,tends to equalize stresses `in the sheave body throughout its length, and fthe lb elt .tension on the portionofthesheave which is centrally supported on the Woodbushing .I9 helps to support the overhung load.

By constructing the `sheave body of Wood plies v onlaminations arranged parallel with the axis andhavingthe grain of the'wood running longitudinally of the body or transversely'of the vgrooves of the-peripheral portion thereof, a -further important vresult -is obtained, namely that the surfaces of the side Walls of the V-grooves are `cut across the grain of -the wood, giving hard durable Wear surfaces for engagement by the v driving belts.

In the illustrative structure, the outermost wood plies or laminations .Landjl dare of greater thickness at their medialportions thanthe depth vofthe beltgrooves l 6, rthe intermediate laminations 2 Yto l3 inclusive being ofless thickness. It will be observed that vthere are no -planes of 'joinder' of t h e wood laminations vonlyJthroughY the side .walls of the ',belztgrooves. lnrotherwords.

The wood bushing I9 is of the solid type as distinguished from a split contractible bushing. In other words, it consists of an unsplit non-contractible wood bushing fitting the hub bore and fitting the shaft to which the sheave is mounted. Sheaves of different sizes or pitch diameters embodying the invention, within certain ranges of pitch diameters, are intended to be madewith hub bores all ofthe same diameter and to be equipped with wood bushings to fit diierentshaft `sizes;Y enabling dealers and also Athe kr'nanu'facturer to carry in stock a relatively small number of each of the different sizes :of sheaves and a relatively large quantity of woodbushings to lit all of said sheaves and to adapt them to different shaft sizes; thus minimizing the quantity of sheaves of ldifferent pitchv diameters which need to be carried in stock. j

The wood bushingr I9 is formed with aninternal longitudinal keyway 2 I in which ts a shaft key 22 by which the bushing is keyed to the shaft. The key 22 `is a conventional metal shaft key'such as is ordinarily used for `*keying a, cast iron sheave to the shaft. The wood bushing is also formed with an external longitudinal groove 23 angularly spaced from the keyway 2l; said groove 23 being engaged by a metallic element embedded in the wood sheave `body for keying the shaft body tothe bushing. n

The wood sheavebody is secured to the sheave shaft by set lscrews'24 and ZSeXtending through and in' threaded engagement with nuts 25` and 21 fitted in recesses therefor'in the wood sheave body, with the screw holes o'f thev nuts in alinement with radial setk screw holes in the body. Said set screws extend through registering holes therefor inthe wood bushing I9 and bear one vagainst the shaft key 22 andthe other directly against the shaft. The nut 21 carrying the set screw 2B constitutes the'element previously re- Hferred to engaging the 'external longitudinal e s et screws arranged at an angle of substantially less than 180 degrees apart. The use of two set screws` soarranged distributes the clamping action and provides a more effective fastening, with less distortion of parts, than would be obtainable with the use of a single set screw. The

most reliable clamping action with least distortion of parts results from the use of two set screws arranged with their radial centersat an angle of v120 degrees. The set screws 24 and 25 in the illustrative sheave are therefore so arranged, the positions-of the vnuts 25-and 21 and the relationship of the Ykey'ways 2| and 23, of the bushing being in accordance with such arrangement.

The nuts 25 and 21 are provided in the form of metal elements of round cross section having transverse threaded holes for engagement by the set screws. These elements, arranged adjacent to and parallel with the hub bore, are fitted in recesses therefor formed in the wood hub body simply by drilling holes therein from its rear end. After the nuts are inserted in the nut holes, these holes may be closed by wood plugs as indicated at 28. This feature of the invention is a substantial factor in economy of construction of thevsheave, since the recesses for the nuts can be easily formed by simply drilling holes parallel with the hub bore. Further, this feature is important from the constructional standpoint, particularly in the case of a wood or other nonmetallic sheave body of small radial thickness between the hub bore and the bottoms of the belt grooves. It will be observed that the diame ter of the cylindrical metal elements constituting the nuts is only about twice the diameter of the set screws. Therefore the nuts occupy but little space in the cross section of the sheave body, as compared with the space that would bev occupied by nuts of ordinary form; and in a sheave body of small radial thickness there may be a substantial radial thickness thereof around the nuts.- Moreover, due to the cylindrical form of the nuts they bear outwardly for half ofY their surfaces, and also bear laterally for half 'of their surfaces, inthe surrounding wood body. The nuts may be considered as embedded inthe sense that they are closely tted in the Vsurrounding wood body and rmly supported thereby against forces tending to' displace the nuts, due to the thrust of the set screws against the shaft and the driving of the sheave body either by the shaft against the load on the belts or by the belts n against the load on the shaft.

The fastening devices consisting of thgnuts and set screws above described may be duplicated so as-to have two setvscr'ews bearing on the shaft key and two others bearing directly against the shaft, as may be desirable in longsheaves having a large number of belt grooves, say ten or more.

lSuch a construction is shown in Fig, 4.

In Fig. 4 the laminated wood body I5a is identical to that first described except that its annular ribs 29 at the ends of the body are thinner than in the rst construction, andin vorder to protect these end portions from chipping the sheave body is provided with adhesively alxed wood caps30. Fitted in the hub bore ofthe sheave body Ils a wood bushing I9a identical to that rst described. The longitudinal keyway in said bushing for engagement with a shaft key is indicated at ZIE. The sheave body is providedewith means forsecuring it to the shaft identical 'to the meansrst described except that the fastening devics'l'are duplicated, there being two set screws 24fx'tending through and in threaded engagernntwith the embedded nuts 25a and screwable against-the shaft key (not shown), and two setsere'wsn extending through and in threaded 4engagement with the vembedded nuts 21a and screwable clirectly against the shaft. The two lpair'sf'*set screws 24a and 2lia are angularly spaced? 120 degrees from radial center to radial center, and the cylindrical metal elements constitutingthe" nuts 21at protrude laterally intothehub bore 4'of the sheave body and engage an external hub groove (notshwn) of the wood bushinglgasinfthe first vdescribed constructonJ- 'The cylindrical `nuts 25b and 2li.

metal elements constituting nuts'ZS-andllalare fitted in holes drilled in the woo'dzsheavevbcdy parallel with the woodsheave'shaft', theinuts of each pair'being spaced bywood plugsll `tted in said holes, andthe holes being lplugged therein by wood plugs 28a.

Fig, shows a wood sheave c-omprising a laminated wood body lh fitted with a wood bushing ISby and having means for securing it'to'the'sheave shaft comprising set screws 2th and 25h engaging `Wth respect to the wood bushing and means for securing the sheave body tothe shaft, the construction isidentical to that nrst described, but the wood sheave body is of different form and construction from the others, being composed ofadhesively united wood discs 32 and end caps33.V v The belt grooves lb are provided by forming adjacent discs 32 with confronting marginal beveled portions forming the side walls of said grooves. A sheave body of this type may be made by adhesively joining preformed wood components. This body construction has certain advantages and is practicable for sheaves centrally supported through the bushing on the shaft for its full length or nearly its full length and having only a short overhanging portion.

Sheaves embodying the invention are of strong and sturdy character, of practicable and eflicient construction., susceptible of economical manufacture, easily installed, and serviceable under many conditions for duties for which the cast iron sheaves of corresponding sizes are commonly employed. The invention therefore offers opportunity for extensive utilization cf wood in the construction of sheaves for multiple V-belt drives and other belt and sheave type drives, as well as for replacement of existing cast iron 01 other metallic sheaves by wood sheaves embodying the invention, with resultant release of much valuable metal for other essential purposes.

Though hard wood is considered the most satisfactory material, it is apparent that sheave bodies of the constructions described can be made as laminated bodies of fiber board or other suitable non-metallic material having the strength, hardness, toughness and cohesiveness suitable for sheave body constructions, considering the duties to be imposed on the sheaves. The means provided by the invention for securing the sheave body to the sheave shaft is also applicable to sheaves having non-metallic bodies formed as one piece articles molded from plastic material.

We claim:

l. A multi-grooved sheave embodying an overhanging or centrally unsupported portion having therein a plurality of the belt grooves of the sheave, the hub and surrounding portion of the sheave and said overhanging portion being in a unitary body composed of wood plies or laminations adhesively joined in planes parallel with the sheave axis, the wood pieces forming the plies or laminations being continuous from end to end of said body.

2'. A multi-grooved sheave of the block type comprising a cylindric body composed of wood laminations adhesively joined in planes parallel with the sheave axis and having the grain of the wood disposed longitudinally, said body being formed with annular belt grooves in its periphery and with a central hub bore, the side walls of said grooves being provided by wood surfaces transverse of the grain of the wood throughout the entire circumference.

3. A sheave comprising a cylindric wood body having `an annularly `grooved periphery and a central'hub bore, a wood bushingfitte'd therein zand.adaptedto iitand to be keyedto the sheave posed o"f adhesively joined plies or laminations of wood or other suitable non-metallic material, there being recesses drilled in said body parallel with and adjacent to the hub bore and' intersecting radial set screw holes, said recesses being of greater diameter than said holes, nuts consisting of cylindrical'elements having transverse set screw holes and tted in said recesses with their holes in ,'line with the set screw holes of said body, and set screws extending through said nuts in threaded engagement therewith whereby to secure said body to the sheave shaft.

5. A sheave comprising a cylindric body of nonmetallic material having an annularlyr grooved periphery and a central hub bore, a non-metallic bushing fitted in said bore and adapted to lt and to be keyed to the shaft to which the sheave is to be applied, said bushing having an internal longitudinal keyway for engagement by a shaft key and an external longitudinal groove angularly spaced from said keyway, correspondingly angularly spaced nuts insetl in said body adjacent to said bore and with their holes disposed radially, one of said nuts engaging said groove to key said bushing to said body, and set screws extending through said nuts in threaded engagement therewith and through holes in said bushing for securing said body to the shaft by clamping said bushing therebetween, one of said set screws adapted to bear against said shaft key and the other directly against the shaft.

6. A sheave comprising a cylindric body of non-metallic material having an annularly grooved periphery and a central hub bore, a nonmetallic bushing fitted therein and adapted to fit and to be keyed to the sheave shaft, said bushing having an internal longitudinal keyway for engagement by ak shaft key and an external 1ongitudinal groove angularly spaced from said keyway, there being correspondingly angularly spaced recesses drilled in said body parallel with and adjacent to said bore, nuts comprising cylindrical metal elements with transverse screw holes fitted in said recesses, the holes thereof being radially disposed, one of said elements engaging said groove for keying the bushing to said sheave body, and radially disposed set screws extending through said elements in threaded engagement therewith and through holes therefor in said bushing whereby to secure said sheave body to the shaft by clamping said bushing therebetween, one of said set screws adapted to bear against said tshaft key and the other directly against the shaf 7. A sheave comprising a non-metallic sheave body, a non-metallic bushing tted therein and adapted to t and to be keyed to the sheave shaft, said bushing having an internal longitudinal keyway for engagement by a shaft key and an external longitudinal groove angularly spaced from said keyway, there being correspondingly angularly spaced pluralites of nuts inset in said body adjacent to said bore with the holes of the nuts disposed radially, spacers of non-metallic material between the nuts of each group, the nuts of one group engaging' said groove to key said'bushing to said body, and set screws extending through said nuts in threaded engagement therewith and through holes therefor in said bushing whereby to clamp the `bushing between the sheave shaft and said body, one group of said screws adapted to bear against said shaft key and in the other bearing directly against the shaft.

8. A sheave comprising a non-metallic sheave body having a central hub bore, there being a recess drilled in said body adjacent to and parallel with said bore, a cylindrical metal element tted in said recess, and a radially disposed set screw extending through said element in threaded engagement therewith and screwable against the shaft for securing said sheave body thereto, said element being supported against outward thrust Y terlal of said body.

9. AL sheave comprising a non-metallic sheave body having a central hub bore, there being a recess drilled in said body adjacent to and parallel with said bore, a cylindrical metal element fitted in said recess, and a radially disposed set screw extending through said element in threaded engagement therewith and screwable against the shaft for securing said sheave body thereto, said element protruding laterally into said bore to function as a key for keying to said body a bushing fitted in said bore, said element being sup ported against outward thrust of said set screw solely by the non-metallic material of said body.

DAVID FIRTH. DONALD P. LOWER. 

